This invention relates to apparatus for feeding a plurality of approximately flat articles, such as envelopes and postcards.
Flat article feeding apparatus of the type described is disclosed in U.S. Pat. No. 4,541,624 issued to Tsutomu Sasage et al and assigned to NEC Corporation. For use typically in a mail sorting system, the apparatus of Sasage et al comprises a feeder for feeding the flat articles to another section such as a sorting section. The feeder comprises an endless feed belt defining a feed plane at a predetermined portion thereof. Ordinarily, the feeder feeds the flat articles one by one with each of the flat articles fed substantially along the feed plane. However, the feeder sometimes feeds two or more of the flat articles at a time to the other section. Feed of two or more of the flat articles will hereafter be called an overlap feed and should be avoided.
In order to avoid the overlap feed, a reversedly driven roller is well known in the art. The reversedly driven roller is urged by a spring towards the feed plane so that the reversedly driven roller is in contact with one of the flat articles that is fed on the feed plane as a particular article. The reversedly driven roller reversedly feeds another flat article overlapping the particular article. As a result, the feed belt feeds only the particular article outwardly of the feed belt.
It is to be noted in this connection that the flat articles, in particular the envelopes, may often have a thick or swelling portion caused by contents of the envelope. In this event, the conventional reversedly driven roller can not avoid the overlap feed. This is because the reversedly driven roller is a single roller and because the reversedly driven roller is brought into contact with only a part of the particular article. The overlap feed causes an unstable feed of the flat articles with at least one of the flat articles in a skewed position.